This dissertation investigates the question: are mission critical occupations more favored than other occupations in performance appraisals in pay pools? While many types of bias in performance appraisals occur, such as gender or race, occupational bias--favoring or showing preference for one occupation over another in performance appraisals and subsequent ratings-- has not been fully examined. There is a lack of empirical evidence that addresses occupational bias in performance appraisal and ratings in the Federal civil service sector, and more specifically the Department of Defense. The importance of occupational bias in performance appraisals is seen in the cost to organization and taxpayer, the degradation to fairness and trust in the workplace, and the erosion of organizational values. The methodology used to address this dissertation's hypothesis is a quantitative-qualitative inquiry that investigates performance ratings of the engineering occupational series within three Department of Defense (DOD) engineering agencies. The methodology is comprised of three parts: quantitative analysis of pay pool rating data and qualitative analysis of archived documents and expert interviews. Each part of the methodology is intended to be mutually supportive. The quantitative analysis yields a null finding of the hypothesis based on two findings. First, indicators of occupational bias were not found using differences of average occupational performance ratings between engineers and other occupations in three DOD engineering organizations. Second, Fiscal Year 2008 engineer occupational series performance ratings in three Department of Defense engineering agencies did not show statistically significant differences when compared to occupations such as personnel management specialists and accountants. This may be due to privacy act limitations in the data set used. Anecdotal evidence of preferences for mission critical occupations in performance appraisals and ratings was found to support the hypothesis. / Ph. D.

Les réseaux de capteurs sans fil sont conçus dans le but de remplir différentes tâches de surveillance dans des conditions environnementales variées. Ces petits appareils électroniques sont capables de détecter, traiter et transmettre des données environnementales avec des communications multi-sauts et peuvent par conséquent aussi se coordonner. En même temps, ces dispositifs ont des ressources limitées (mémoire, capacités de calcul) et doivent fonctionner le plus souvent sur des batteries. C’est pour ces raisons que les recherches menées dans le domaine des réseaux de capteurs possèdent naturellement une forte partie qui concerne la réduction de la consommation d’énergie et une auto-organisation du réseau.Nos recherches considèrent les applications critiques de surveillance. Ces applications peuvent avoir des exigences très différentes des réseaux de capteurs traditionnels. De plus, nous utilisons des capteurs images, dont l’activité est définie en fonction de la criticité de l’application. Un ordonnancement basé sur la criticité permet de définir des nœuds sentinelles qui possèderont une vitesse de capture plus grande, cela afin d’avoir une probabilité plus élevée de détecter des intrusions et d’alerter leurs nœuds voisins. Au niveau de la couche de contrôle d’accès au medium (couche MAC), les approches alternant activité-sommeil (consistant à allumer et éteindre la radio de manière cyclique) sont utilisées pour préserver l’énergie et prolonger la durée de vie du réseau. Cependant, tout en conservant l’énergie, les applications critiques de surveillance ne doivent pas compromettre la qualité de la surveillance et le réseau doit être toujours en mesure de propager rapidement les messages d’alerte. Notre but est de définir un protocole MAC qui pourrait réduire la latence de propagation d’alerte ainsi que de prolonger la durée de vie du réseau. Nous proposons tout d’abord une approche originale pour déterminer dynamiquement la durée de la période d’activité radio des nœuds pour augmenter la probabilité de propager rapidement les alertes. Les résultats des simulations ont confirmé que notre approche réussit à améliorer la réactivité du système par rapport à une approche statique. En même temps, notre proposition permet de réduire considérablement la consommation d’énergie du réseau. Ensuite, nous avons implémenter notre approche sur des capteurs réels et les résultats obtenus sont très proches des résultats de simulation. / Wireless Sensor Networks (WSNs) are designed for the purpose of completing different monitoring tasks under various environmental conditions. The small electronic devices called sensors are capable of sensing, processing and communicating the environmental data through multi-hop communication and coordination. These devices have limited resources (memory, computing capabilities) and usually run on batteries. This is the reason the research on wireless sensor networks have been focused on energy efficiency and self-organization of the network. We consider mission-critical surveillance applications in our research work. These applications can have different requirements than traditional WSNs. In addition, we use image sensor nodes, whose activity is defined based on criticality of the application. The criticality-based scheduling scheme defines sentry nodes with faster capture rates, to have higher probability to detect intrusions and to alert neighbor nodes. At Medium Access Control (MAC) Layer level, duty cycled approaches are used to preserve energy and prolong the network lifetime. However, while conserving energy, mission-critical surveillance applications cannot compromise on quality of surveillance and the network should still be able to quickly propagate the alert messages. In this thesis, we propose a low latency, energy efficient adaptive MAC protocol. We first propose an original approach to dynamically determine the duty-cycle length of sensor nodes to increase the probability of quick propagation of alerts. Simulation results confirmed that our approach succeeds in improving the system responsiveness when compared to a static duty-cycling approach. At the same time, our proposition considerably reduces the energy consumption of the network. Then, we implemented our approach on sensor node hardware and results were found to be very close to our simulation results.

In recent years, the ever-increasing environmental friendliness concern has made energy efficiency in telecom networks as an important theme in their operations. Meanwhile, mission-critical (MC) services and systems (such as healthcare, police, and firefighting) have been acquiring special attention from telecom designers and operators. The currently deployed MC network technologies are indigent in terms of bandwidth capacity, and thus they are not able to support the emerging MC multimedia applications. Therefore in this thesis, we first explore the possibility of provisioning the MC services over the integration of fiber-wireless (FiWi) technologies, which has been considered as a promising candidate for the deployment of high-speed and mobile broadband access networks. We then investigate the energy efficiency problem in the FiWi integration, which consists of WiMAX in the wireless plane, and of Ethernet Passive Optical Network (EPON) - the most popular variant of the next-generation PON (NG-PON) technology, in the optical plane. In WiMAX, the energy saving protocol has been extensively investigated and standardized. Conversely, it has been recently studied in NG-PON, which currently consumes the least power among all the high-speed access networks. However, NG-PON has notably matured in the past few years and is envisioned to massively evolve in the near future. This trend will increase the power requirements of NG-PON and make it no longer coveted. Therefore we address the energy efficiency problem in NG-PON. For each of our contributions, we conduct extensive simulations to demonstrate the effectiveness and advantages of the proposed solutions.

Mission-critical system typically refers to a project or system for which the success is vital to the mission of the underlying organization. The failure or delayed completion of the tasks in mission-critical systems may cause severe financial loss, even human casualties. For example, failure of an accurate and timely forecast of Hurricane Rita in September 2005 caused enormous financial loss and several deaths. As such, real-time guarantee and reliability have always been two key foci of mission-critical system design. Many factors affect real-time guarantee and reliability. From the software design perspective, which is the focus of this paper, three aspects are most important. The first of these is how to design a single application to effectively support real-time requirement and improve reliability, the second is how to integrate different applications in a cluster environment to guarantee real-time requirement and improve reliability, and the third is how to effectively coordinate distributed applications to support real-time requirements and improve reliability. Following these three aspects, this dissertation proposes and implements three novel methodologies: real-time component based single node application development, real-time workflow-based cluster application integration, and real-time distributed admission control. For ease of understanding, we introduce these three methodologies and implementations in three real-world mission-critical application systems: single node mission-critical system, cluster environment mission-critical system, and wide-area network mission-critical system. We study full-scale design and implementation of these mission-critical systems, more specifically: 1) For the single node system, we introduce a real-time component based application model, a novel design methodology, and based on the model and methodology, we implement a real-time component based Enterprise JavaBean (EJB) System. Through component based design, efficient resource management and scheduling, we show that our model and design methodology can effectively improve system reliability and guarantee real-time requirement. 2) For the system in a cluster environment, we introduce a new application model, a real-time workflow-based application integration methodology, and based on the model and methodology, we implement a data center management system for the Southeastern Universities Research Association (SURA) project. We show that our methodology can greatly simplify the design of such a system and make it easier to meet deadline requirements, while improving system reliability through the reuse of fully tested legacy models. 3) For the system in a wide area network, we narrow our focus to a representative VoIP system and introduce a general distributed real-time VoIP system model, a novel system design methodology, and an implementation. We show that with our new model and architectural design mechanism, we can provide effective real-time requirement for Voice over Internet Protocol (VoIP).

In recent years, the ever-increasing environmental friendliness concern has made energy efficiency in telecom networks as an important theme in their operations. Meanwhile, mission-critical (MC) services and systems (such as healthcare, police, and firefighting) have been acquiring special attention from telecom designers and operators. The currently deployed MC network technologies are indigent in terms of bandwidth capacity, and thus they are not able to support the emerging MC multimedia applications. Therefore in this thesis, we first explore the possibility of provisioning the MC services over the integration of fiber-wireless (FiWi) technologies, which has been considered as a promising candidate for the deployment of high-speed and mobile broadband access networks. We then investigate the energy efficiency problem in the FiWi integration, which consists of WiMAX in the wireless plane, and of Ethernet Passive Optical Network (EPON) - the most popular variant of the next-generation PON (NG-PON) technology, in the optical plane. In WiMAX, the energy saving protocol has been extensively investigated and standardized. Conversely, it has been recently studied in NG-PON, which currently consumes the least power among all the high-speed access networks. However, NG-PON has notably matured in the past few years and is envisioned to massively evolve in the near future. This trend will increase the power requirements of NG-PON and make it no longer coveted. Therefore we address the energy efficiency problem in NG-PON. For each of our contributions, we conduct extensive simulations to demonstrate the effectiveness and advantages of the proposed solutions.

Hardware sizing has come to play an important role when designing and implementing business critical applications because it is crucial that the existing or defined business and application requirements are interpreted into an appropriate hardware configuration. If it is not done correctly, it may destabilize the environment which means interruptions and unplanned downtimes that in turn will cause business loosing not only vital revenue but also customer confidence in the process. This is one of the reasons for why hardware sizing has become a discipline of its own and as such, each combination of workload and hardware configuration is treated differently. Many application vendors have their own set of tools and recommendations to perform the sizing. Once the sizing is performed, the results can be mapped to hardware that is already benchmarked. This also means the hardware can be configured specially to support the application workload in question. It also implies that sizing is one of the major activities when creating a technical architecture where it is used to select the right hardware.   The purpose of this document is to perform a complete sizing exercise based on the requirements for a mission critical business application and then translate them into an appropriate hardware configuration. Furthermore, a set of sizing methodologies and tools are analyzed in detail as well in order to give an as vendor neutral view as possible. Specific requirements such as high availability, scalability and other important areas are also taken into consideration when designing and creating the hardware architecture.

Mission-critical facilities house operations that when interrupted, can prove disastrous to an organization’s future. Limited market research is available to determine what roof types are best suited to meet the unique demands of these buildings. The purpose of this research was to evaluate different roof materials and to observe trends relative to their lifecycle costs and roof professional’s assessment in use with mission-critical facilities. The objectives of the study were to determine the average annual lifecycle costs for the sampled roof materials, to determine the roofing professionals’ preferred mission-critical facility roof materials, and to priority rank the sampled roof materials for use with mission-critical facilities A pilot study was conducted to assess variables in evaluating different roof materials and their use with mission-critical facilities. Additionally, a survey was administered to roofing professionals across the United States to obtain lifecycle cost information for various roof materials as well as ratings for those materials for use with mission-critical facilities. The research found that single-ply roofs, with the exception of 60 Mil TPO, had lower annual lifecycle costs than built-up roofs due to their having lower install and removal costs, as well as having increasing life expectancies over the years. The metal roof selection was also shown to have a low annual lifecycle cost due to having the longest estimated lifespan. Built-up and metal roofs were rated highest by roofing professionals for their use with mission-critical facilities, suggesting a prioritization of risk reduction versus cost savings. When the lifecycle cost data was applied to the roof material ratings, the data showed that built-up roofs presented themselves as good values for mission-critical facilities; however, 90 Mil EPDM and 24-gauge metal roofs could be considered as viable cost savings alternatives.

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